Conventional aircraft engines, ramjets, combined-cycle engines and industrial burners typically include an electronically actuated ignition source for initiating a combustion event in a combustion chamber. Such electronically actuated ignition sources are usually of the spark igniter type or the plasma jet type.
Spark igniters typically utilize a spark plug-like device for generating a discharge arc which is employed to generate a flame kernel that ignites a mixture of fuel and oxidizer (e.g., air or oxygen) in the combustion chamber. Plasma jet igniters typically employ a fuel source, such as hydrogen or jet fuel, that dissociates in a spark discharge to produce a kernel of various radicals that in turn initiate a combustion event in the combustion chamber.
If the rate of heat loss from the kernel is less than the rate of heat production in the kernel, the ignition front advances leading to combustor light-off. Most conventional igniters require favorable aerodynamic conditions to advance the ignition front. Some combustors, however, are engineered to operate with inlet conditions (e.g., during supersonic pre-ignition flow) and/or fuel conditions (e.g., fuel type, fuel droplet size, the extent to which the fuel and air have mixed) that do not present the favorable aerodynamic conditions that are necessary for reliable ignition and flame propagation with conventional igniters. Further aggravating this situation, it may not be practical to place the igniter relative to the combustor in the position where it would be most effective as when, for example, the placement of the igniter is dictated by concerns for serviceability or the packaging of the combustor into an application. Accordingly, there remains a need in the art for an improved igniter.